Recent research has identified neonatal white matter damage as the strongest predictor of cerebral palsy among infants born very preterm. Transient hypothyroxinemia of prematurity also appears to be strongly predictive of motor and cognitive impairments in early childhood. These findings raise a new set of important questions to be addressed in this protocol regarding (a) general and specific neuropsychological sequelae of early brain injury associated with preterm birth; (b) the role of environmental stimulation in recovery of function and prevention of cognitive deficits; and (c) how the human brain develops in repsonse to specific neonatal insults. The sampling and study design will allow investigation of potential confounding and modifying effects of motor, vision, and hearing impairments, as well as socioeconomic status, on the relationship between early brain injury and cognitive development. The study sample will consist of children previously enrolled in the Developmental Epidemiology Network Study. The DEN study investigated the frequency and antecedents of neonatal white matter lesions in very preterm infants. Each child who is enrolled will receive a general neuropsychological assessment, including a battery of cognitive and motor tests and a neurological evaluation. parental interviews will be conducted to obtain a child's developmental and medical history.